Catalyzed Oxidations with

An exception is, of course, metal-catalyzed oxidation with molecular oxygen. 

Manufacture. Historically, ammonium nitrate was manufactured by a double decomposition method using sodium nitrate and either ammonium sulfate or ammonium chloride. Modem commercial processes, however, rely almost exclusively on the neutralization of nitric acid (qv), produced from ammonia through catalyzed oxidation, with ammonia. Manufacturers commonly use onsite ammonia although some ammonium nitrate is made from purchased ammonia. SoHd product used as fertilizer has been the predominant form produced. However, sale of ammonium nitrate as a component in urea—ammonium nitrate Hquid fertilizer has grown to where about half the ammonium nitrate produced is actually marketed as a solution. 

Figure 25. Bromide-catalyzed oxidation with NaOCl.

Drivers for Performing Catalyzed Oxidations with HjOj in Micro Reactors... 

Finally, the hydrazide 29 98> is strongly fluorescent in neutral solution (e.g. in dioxane), the fluorescence intensity amounting to about 200% of that of 7-dimethylamino-naphthalene-1.2 dicarboxylic hydrazide 30, which is one of the best chemiluminescent hydrazides 97b The 5-isomer, however, is very poor in chemiluminescence in an aqueous system (hemin-catalyzed oxidation with aqueous alkaline hydrogen peroxide), the light yield being only 1 % of that of the 7-isomer in DMSO/t-Bu0K/02 its quantum yield is slightly better but very distinctly below that of 30 98>">. It should be mentioned that in aqueous alkaline solu-... 

Accent [Aqueous carbon compound effluent treatment] A process for oxidizing organic contaminants in aqueous streams by catalyzed oxidation with sodium hypochlorite. The catalyst is promoted nickel oxide, which retains active oxygen at its surface, as well as adsorbing the organics. Developed by ICI Katalco and first offered in 1998. 

CATAZONE [catalyzed ozone] A process for removing traces of organic compounds from groundwater by catalyzed oxidation with ozone. The catalyst is titanium dioxide, and hydrogen peroxide may be added as well. 

WOX [Wet oxidation] A process for destroying organic materials by catalyzed oxidation with hydrogen peroxide. Developed by ASEA Atom, Sweden. See also WINWOX... 

The palladium-catalyzed reaction of benzol]quinoline in the presence of PhI(OAc)2 as an oxidant in MeCN gives an 11 1 mixture of 10-acetoxy- and 10-hydroxybenzo[ ]quinolines in 86% yield (Equation (98)).135 This chelation-directed oxidation can be extended to the benzylic C-H bond of 8-methylquinoline. The inactivated sp3 C-H bonds of oximes and pyridines undergo the same palladium-catalyzed oxidation with PhI(OAc)2 (Equation (99)).1... 

The conventional synthesis of trans-2,5-dialkyl phospholanes starting from a chiral 1,4-diol is shown in Scheme 24.1. Originally, these 1,4-diols were obtained via electrochemical Kolbe coupling of single enantiomer a-hydroxy adds [25], but this method proved to be commercially impracticable and has since been replaced by more viable biocatalytic routes [26]. Reaction of the chiral 1,4-diol with thionyl chloride followed by ruthenium-catalyzed oxidation with so-... 

Scheme 6.30 CPO-catalyzed oxidations with hydrogen peroxide.

The accepted mechanistic scheme for metal catalyzed oxidations with peroxides is sketched in Scheme 1. The features of the active oxidant depend on the nature of the oxygen donor and on its interaction with the metal precursor in several examples high-valent peroxo metal species have been recognized as competent intermediates ... 

In the earlier volume of this book, the chapter dedicated to transition metal peroxides, written by Mimoun , gave a detailed description of the features of the identified peroxo species and a survey of their reactivity toward hydrocarbons. Here we begin from the point where Mimoun ended, thus we shall analyze the achievements made in the field in the last 20 years. In the first part of our chapter we shall review the newest species identified and characterized as an example we shall discuss in detail an important breakthrough, made more than ten years ago by Herrmann and coworkers who identified mono- and di-peroxo derivatives of methyl-trioxorhenium. With this catalyst, as we shall see in detail later on in the chapter, several remarkable oxidative processes have been developed. Attention will be paid to peroxy and hydroperoxide derivatives, very nnconunon species in 1982. Interesting aspects of the speciation of peroxo and peroxy complexes in solntion, made with the aid of spectroscopic and spectrometric techniqnes, will be also considered. The mechanistic aspects of the metal catalyzed oxidations with peroxides will be only shortly reviewed, with particular attention to some achievements obtained mainly with theoretical calculations. Indeed, for quite a long time there was an active debate in the literature regarding the possible mechanisms operating in particular with nucleophilic substrates. This central theme has been already very well described and discussed, so interested readers are referred to published reviews and book chapters . 

The second part of the chapter will be dedicated to the reactivity of transition metal peroxides, either isolated or formed in solution in catalytic processes, toward several classes of substrates. Hopefully this survey, where particular emphasis is placed on the selectivity aspects of these reactions, will present to the readers the potential of metal catalyzed oxidations with peroxides and highlight the perspective for researchers in the field. 

The intermediate formation of alkyl peroxide complexes has been postulated, and in several cases observed with spectroscopic and spectrometric techniques in several selective procedures based on metal catalyzed oxidation with hydroperoxides, Ti and V ions being among the transition metals most widely used for this purpose. However, to date the few examples of alkyl peroxide complexes isolated and characterized in the solid state refer to (dipic)V0(00Bu-f)(H20) 8, synthesized by Mimoun and coworkers in 1983, and to a dimeric Ti complex [((/7 -OOBu-f)titanatrane)2(CH2Cl2)3] 9, synthesized by Boche and coworkers. ... 

With this chapter we hope that newcomers to the field have received a taste of how active is the research in metal-catalyzed oxidation with peroxides, and also in fntnre perspectives of greener and more efficient oxidative protocols. Additionally, we hope that people deeply involved in this area will appreciate the collection of the main literatnre that has been published in these last 20 years. 

In summary, the uncatalyzed oxidation of S(IV) occurs in aqueous solution but is very slow. However, given the ubiquitous occurrence of Fe3+ and Mn2+ (see Chapter 9), the uncatalyzed oxidation is likely irrelevant to atmospheric solutions. The catalyzed oxidations are complex in both kinetics and mechanism. We shall defer a comparison of their importance until other oxidation mechanisms are discussed. However, we shall see that the catalyzed oxidations are likely to contribute significantly to S(IV) oxidation in solution only at pH values near neutral, i.e., in the range of 6-7. As the oxidation occurs and acid forms, the pH falls. The rapid falloff in the rate of the catalyzed oxidation with increasing [H + ] then results in a rapid quenching of this path, as expected from Fig. 8.9a. 

Selective oxidation of alcohols. Primary alcohols are oxidized by this RuCL complex about 50 times as rapidly as secondary alcohols. Use of benzene as solvent is critical lor this high selectivity. Little or no reaction occurs in CH3CN, THF, or DMF. Most oxidants, if they show any selectivity, oxidize secondary alcohols more rapidly than primary ones. However, ruthenium-catalyzed oxidations with N-mcthylmorpholine N-nxide and oxidations with PCC4 proceed about three times as rapidly with primary alcohols as with secondary ones. 

Several Pd-catalyzed oxidations with different reoxidants have been developed. In these reactions PdCl2 or Pd(OAc)2 in acetic acid is usually employed, with tert-BuOOH and Te02,699 or p-benzoquinone and MnO2 70°... 

Oxidation to Phenols. Direct hydroxylation of benzene to phenol can be achieved in a free-radical process with H202 or 02 as oxidants.739-744 Metal ions [Fe(II), Cu(II), Ti(HI)] may be used to catalyze oxidation with H202. Of these reactions, the so-called Fenton-type oxidation is the most widely studied process.742 Oxidation in the presence of iron(II) sulfate was reported in early studies to yield phenol. Since phenol exhibits higher reactivity than benzene, varying amounts of isomeric dihydroxybenzenes were also formed. 

Oxidation of the crude product mixtures containing both regioisomers 44 and 45 gave Cbz-protected amino acid 46 and amino ketone 47, which could then be separated by simple acid-base-extraction. As oxidizing reagents, periodic acid and a catalytic amount of ruthenium trichloride were found to be suitable. For some cases in which chemical yields were low, a TEMPO-catalyzed oxidation with bleach as oxidant was more effective. 

Furan-2,5-dicarboxylic add also has tremendous industrial potential, because it could replace oil-derived diadds such as adipic or terephthalic acid as monomers for polyesters and polyamides [98, 99]. This diadd can be synthesized by Pt-catalyzed oxidation with 02 of 5-hydroxymethylfurfural the latter is obtained by acid-catalyzed dehydration of D-frudose or frudosans (inulin) the latter, however, are too expensive as starting materials, and yields from glucose-based waste raw materials are no higher than 40%. Therefore, the potential attractive option of furan-2,5-dicarboxylic acid will develop only after an effident generation of 5-hydroxymethylfurfural from forestry waste materials has been developed. The same compound is also the starting material for the synthesis of other interesting chemicals obtained by oxidative processes, such as 5-hydroxymethylfuroic add, 5-formylfuran-2-carboxylic add and the 1,6-dialdehyde. 

Sundstrom, D.W., Klei, H.E., Nalette, T.A., Reidy, D.J., and Weir, B.A., Destruction of halogenated aliphatic by ultraviolet catalyzed oxidation with hydrogen peroxide, J. Hazardous Waste Hazardous Mater., 3, 101, 1986. 

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